1. Field of the Invention
The present invention relates to a magnetic head slider assembly comprising a magnetic head slider and a support body supporting the magnetic head slider and to a magnetic disk apparatus, and more particularly to a magnetic head slider assembly and a magnetic disk apparatus having high recording density and high reliability.
2. Description of the Prior Art
In recent years, the recording density of a magnetic disk apparatus (hereinafter, referred to as the apparatus) becomes high, so that the high reliability and the low floating is required for a head disk interface (HDI). A magnetic head slider is intermittently brought into contact with a medium surface when the floating amount (i.e. flying height) thereof is equal to or less than 10 nm, while it may be continuously brought into contact with the medium surface when the floating amount is equal to or less than 5 nm. In the conventional floating type recording system, the floating amount has been reduced by reducing the size and weight of the slider, however, in the case that the floating amount is equal to or less than 10 nm, a new type of recording system which is different from the floating type becomes required.
In a floating and contacting type recording system described in JP-A-06-060329, two rail surfaces capable of acting as an air bearing are provided on an inflow end of the conventional float recording type of compact slider so as to float the slider, and one contact surface having a magnetic transducer and being hard to act as an air bearing is provided on an outflow end, so that the recording and reproduction are performed while subjecting the contact surface to xe2x80x9cthe following and contacting movementxe2x80x9d with respect to the recording medium surface. In accordance with this recording system, it is possible to reduce the magnetic recording spacing loss between a magnetic transducer gap portion and a magnetic film surface, so that the magnetic recording density can be dramatically improved.
Since the difference between a pressing load and a floating force causes a contact force in the floating contact recording system, it is possible to make the contact force substantially zero by designing the slider so that the minimum floating amount at the outflow end corresponds to a floating amount at a time when the slider starts contacting (namely, a contact start floating amount). However, due to the difference between disk peripheral speeds at the innermost periphery and the outermost periphery of the disk, the floating amount of the slider changes in accordance with the movement of the slider in the disk radial direction, so that the change of the floating amount appears as a change of the contact force, which causes contact vibration and abrasion of the slider. Accordingly, in order to realize a low floating slider having a floating amount equal to or less than 10 nm, it is required to flatten the floating profile, namely the track of the floating amount between the innermost periphery and the outermost periphery of the disk.
Further, in order to effectively increase the recording capacity per one disk, it is necessary to make the liner recording density between the innermost periphery and the outermost periphery of the disk uniform. In order to realize this, it is required to employ a magnetic resistance effective type of head having high sensitivity, of which the reproduction output relates only to the intensity of magnetic field generated by the medium, and to flatten the floating profile in a floating property of the magnetic head slider.
In the case of positioning the head by using the conventional rotary actuator system, the change of the floating amount (flying height) between the disk innermost periphery and the outermost periphery is caused by the change of the peripheral speed due to the difference of radial positions of the innermost and outermost peripheries, and by the change of a yaw angle showing an air inflow angle.
A magnetic head slider of the conventional floating type recording system described in JP-A-06-325530 is brought into contact with the medium surface when the disk stops, and comprises a floating surface capable of acting as an air bearing and a stepped surface provided in an air inflow direction via a difference portion. A depth xcex4s of the difference portion is less than 500 nm, and a ratio W/L between a length L of the slider in the air inflow direction and a length W in a direction perpendicular to the air inflow direction is equal to or less than 0.3. This structure satisfies the floating characteristic in which the floating amount is not changed with the change of the peripheral speed, however, it is not possible to satisfy the floating characteristic in which the floating amount does not change with the change of the yaw angle due to the difference of radial positions of the innermost and outermost peripheries.
A magnetic head slider of a conventional floating type recording system described in JP-A-05-028682 is structured such that a pair of rails constituted by two surfaces which comprise a flat surface portion inclined in a side of an air stream inflow end and a flat surface portion extending to an outflow end and may act as an air bearing are provided in parallel along both sides. The slider is arranged so that a load supporting point is shifted to the inflow side from the center in the air stream direction of the slider, and a moment applying means is provided for correcting the unbalance of the floating force caused by the shift of the load supporting point. For applying the moment, a slider mounting surface of a gimbal is previously set to have an inclined angle, or a rail width at the air stream inflow end side is structured so as to be wider than a rail width at the outflow end side. In accordance with these structures, the change of the floating amount at the outflow end side of the slider with respect to the load change becomes small.
A magnetic head slider of the conventional floating contact type recording system described in U.S. Pat. No. 5,612,839 is structured such that a pair of rails constituted by two surfaces which comprise a flat surface portion inclined in a side of an air stream inflow end and a flat surface portion extending to an outflow end and may act as an air bearing are provided in parallel along both sides. Further, in order to reduce the damage on the magnetic recording medium surface by contact, a corner of the outflow end of the slider rail, which forms a contact surface, is rounded so as to reduce the contact stress. Furthermore, in the case of separating the floating force balancing with the load applied from the support body into a positive pressure generated in a direction of floating the slider and a negative pressure generated in a direction of moving close to the medium surface, a distance x1 between the center position of the positive pressure and an air stream inflow end position of the slider, a distance xp between a position of a load application point and the air stream inflow end position, a slider attitude angle xcex8 in a pitch direction of the slider, and a total length L of the slider in a longitudinal direction satisfy the following relational expression.
0.05xe2x89xa6x1/Lxe2x89xa60.49 
0.05xe2x89xa6xp/Lxe2x89xa60.49 
1.05xe2x89xa6xp/x1xe2x89xa61.2 
0.0003 degxe2x89xa6xcex8xe2x89xa60.0006 deg 
In accordance with the structure in which the load supporting point is shifted to the position in the side of the air stream inflow end of the slider, it is possible to reduce the contact force at a time of contacting. However, it is impossible to obtain the floating characteristic that the floating amount is not changed with respect to both of the peripheral speed change due to the difference of the radial positions between the innermost and outermost peripheries and the change of the yaw angle showing the air stream inflow angle.
In the conventional magnetic head slider mentioned above, since it is not possible to simultaneously satisfy the floating characteristic in which the floating amount is not changed with respect to the change of peripheral speed due to the difference of the radial positions between the innermost and outermost peripheries and the change of the yaw angle showing the air stream inflow angle and it is not possible to reduce the difference of the floating amounts in the floating profile, it is impossible to reduce the contact force change at a time of floating and contacting between the innermost periphery and the outermost periphery of the disk, and to make the liner recording density between the innermost periphery and the outermost periphery of the disk constant.
An object of the present invention is to simultaneously satisfy a floating characteristic in which the floating amount is not changed in accordance with the change of the peripheral speed due to the difference of radial positions of the innermost and outermost peripheries of a disk, and a floating characteristic in which the floating amount is not changed in accordance with the change of a yaw angle corresponding to an air stream inflow angle, thereby reducing the difference of the floating amount in a floating profile.
The inventors have achieved the present invention as a result of executing experiments and calculations on the assumption of various cases of a shape of a floating surface, a height of a stepped surface, a magnitude of the xp mentioned above and the like with respect to the magnetic head slider provided with two stages of stepped surfaces, and studying the obtained results. In this case, the inventors have achieved the present invention by studying so as to set the difference of the floating amount to be equal to or less than 0.8 nm in the case of the relation of xp/Lxe2x89xa60.5, and set the difference of the floating amount to be equal to or less than 3 nm in the case of the relation of 0.5 less than xp/L.
That is, the object mentioned above can be achieved by a magnetic head slider assembly comprising a magnetic head slider provided with an inflow pad (i.e. a front pad) and an outflow pad (i.e. a leading pad) on an opposing side thereof to a magnetic disk surface, and with two stepped surfaces formed on the opposing side via a difference portion and disposed in a direction apart from the magnetic disk surface with respect to contact surfaces of the inflow pad and the outflow pad; and a support body for supporting the magnetic head slider on the magnetic surface, which is provided with a dimple for applying a load to the magnetic head slider, wherein a ratio xcex4s/xcex4r between a depth xcex4s from the contact surfaces to the first stepped surface and a depth xcex4r from the contact surfaces to the second stepped surface is set in a range satisfying a condition shown by 0.047xe2x89xa6xcex4s/xcex4rxe2x89xa60.364, and a ratio xp/L between a length L of the magnetic head slider in an air stream inflow direction and a distance xp between an air stream inflow end of the magnetic head slider and a dimple position is set in a range satisfying a condition shown by 0.002xe2x89xa6xp/Lxe2x89xa60.4.
The ranges of the ratios xcex4s/xcex4r, and xp/L may be set to 0.008xe2x89xa6xcex4s/xcex4rxe2x89xa60.025 and 0.55xe2x89xa6xp/L.